JPH0690464A - Image recorder - Google Patents

Abstract

PURPOSE:To provide an image recorder which is constituted to immediately obtain a white balance set value for moving image recording also when a still- picture recording is performed by using an external light emitting element such as a stroboscope. CONSTITUTION:When a stroboscope 400 is used as auxiliary light when a still image is fetched in a still photographing mode, the white balance just before an electric flash light emitting is performed is stored by a storage means, the electric flash light emitting is performed by compulsorily setting a white balance set value to a prescribed value conformed to the color temperature of the stroboscope, and the value is returned to the white balance set value stored in the storage means just after the still photographing for which the storoboscope is used is terminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus capable of recording still images as well as moving images.

More specifically, the present invention relates to a camera-integrated VT that records a still image together with an external device such as a strobe.
The present invention relates to an image recording device applicable to R (video tape recorder) and the like.

[0003]

2. Description of the Related Art Currently known camera-integrated VTRs are capable of recording not only moving images but also still images. Further, in the field of magnetic recording, there is an increasing demand for high-density recording, and even in VTRs, the tape running speed is reduced to perform higher-density magnetic recording.

When the running speed of the tape decreases, for example, when an audio signal is recorded by using a fixed head, the relative speed cannot be increased and the reproduced sound quality deteriorates. As one means for solving this, there is a method in which the length of the track scanned by the rotary head is made longer than in the conventional case and the time-axis-compressed audio signal is sequentially recorded in the extended portion. Specifically, in the rotary 2-head helical scan type VTR, the magnetic tape was wound around 180 degrees or more on the conventional rotary cylinder, whereas in this method, it was wound around (180 + θ) degrees or more and was additionally wound. This is a method of recording an audio signal that is PCM and time-axis compressed in the "θ" portion.

FIG. 5 is a diagram showing a tape traveling system of such a VTR, and FIG. 6 is a diagram showing recording tracks on a magnetic tape by the VTR shown in FIG. In these figures, 1 is a magnetic tape, 2 is a rotating cylinder, and 3 and 4 are cylinders 2.
Attached to the head, 5 is the video signal recording area of the track formed on the tape 1, and 6 is the PCM.
This is an audio signal recording area portion. The video signal recording area 5 is traced by the heads 3 and 4 by 180 degrees of the rotary cylinder 2, and the PCM audio signal recording area 6 is traced by θ of the rotary cylinder 2.

As described above, as an example of applying the method of recording a digital signal in another area while recording a video signal, it has been proposed to record a still image in the PCM signal recording area 6 as a digital signal. There is. If the image is a still image, it is possible to record all the information on the magnetic tape by scanning the PCM area a plurality of times.

According to this method, not only the still image can be shot using the same recording medium as the moving image shooting apparatus but also the same recording medium can be used by stopping the tape running as in the conventional VTR. It is possible to obtain a high-quality still image from a still image that reproduces a signal.

[0008]

However, in the above-mentioned VTR capable of recording moving images / still images, when the strobe for still image shooting is emitted during the automatic white balance operation which is usually used, the strobe emission is performed. Since the color temperature is higher than the color temperature of normal light, it is necessary to reset the white balance for still image shooting.

However, when the white balance is reset according to the color temperature of the flash, the white balance set value remains set for the moving image immediately after the end of the still image shooting, and the automatic white balance circuit operates. As a result, an image with an unfavorable color balance is recorded until the proper white balance is restored.

Therefore, in view of the above points, an object of the present invention is to provide an image configured such that a white balance set value for recording a moving image can be immediately obtained even when a still image is recorded using an external light emitting element such as a strobe. To provide a recording device.

[0011]

In order to achieve such an object, the present invention provides an automatic white balance function in an image recording apparatus capable of switching between moving image recording and still image recording when recording a still image. When operating the auxiliary light emitting element, a correction unit that corrects the white balance in accordance with the emission characteristics of the light emitting element, and a storage unit that stores the white balance setting value immediately before the still image recording, And a control unit for returning the white balance to the white balance setting value stored in the storage unit after the still image recording is completed.

[0012]

According to the above configuration of the present invention, the storage means for storing the set value of the white balance is provided, and when the moving image is recorded in the general movie mode, the white balance is adjusted by the conventional automatic white balance circuit. When an external strobe is used as auxiliary light when capturing still images in still shooting mode, the white balance immediately before flash firing is stored in the storage device and the white balance setting value is set. When a still image is recorded by forcibly setting a predetermined value that matches the color temperature of the flash and firing the flash, and returning to the white balance setting value stored in the storage unit immediately after the still shooting using the flash is completed. Immediately after moving to movie recording,
It is possible to obtain a still image adjusted to an appropriate white balance.

[0013]

EXAMPLES Examples of the present invention will be described in detail below.

In one embodiment of the present invention, which will be described in detail below, is a recording apparatus having a moving image recording means for recording a video signal output from a video camera and a still image recording means for recording the video signal as a still image. A strobe used as auxiliary light when recording the still image, a light emission timing control unit that controls the light emission timing of the strobe, and a correction value of a white correction (white balance) circuit of the video camera are set to a predetermined value when the strobe emits light. It is provided with a unit for setting a correction value, a storage unit for storing the white balance correction value immediately before the still image shooting, and a unit for returning the white balance correction value to the data stored in the recording unit after the still image shooting. .

FIG. 1 is a block diagram showing the structure of a video camera to which the present invention is applied. Here, 100 is a lens unit, 200 is a camera unit, 300 is a recorder unit, and 400 is a strobe.

In the lens section 100, 11 is a lens,
12 is a diaphragm, 13 is a focus encoder that detects the position between the distances of the lens 11 and obtains distance information to the subject,
Reference numeral 14 is a zoom encoder that obtains focal length information of the lens 11, 15 is an iris encoder that detects the F value of the diaphragm 12, and 16 is an IG meter that drives the diaphragm 12.

In the camera unit 200, 201 is an image pickup device for converting the subject image projected by the lens unit 100 into an electric signal, and 202 is an output from the image pickup device 201 sample-holded for each pixel and amplified to an appropriate level. Sample-hold circuit 203, sample-hold circuit 20
An AGC (automatic gain control) circuit for automatically changing the amplification level so that the output level of 2 becomes a constant level, 204
Is a gamma correction circuit for gamma-correcting the output of the AGC circuit 203, 205 is a matrix circuit for converting the output of the gamma correction circuit 204 into a luminance signal Y and color difference signals BY and RY, and 206 is an output of the matrix circuit 205. NTSC
An encoder circuit for converting to a standardized signal such as 20
Reference numeral 7 is a sync signal generating circuit for generating horizontal and vertical sync signals, and 208 is an image pickup device 201 in accordance with the horizontal and vertical sync signals obtained from the sync signal generating circuit 207.
A driver circuit 209 for scanning the lens unit 1 so that the output level of the sample hold circuit 202 becomes constant.
00 is an auto iris circuit for driving the aperture 12 of the 00 by the IG meter 16, 210 is an AWB (automatic white balance) circuit for controlling the color balance of the output of the matrix circuit 205, and 211 is the AWB circuit 210 for stroboscopic photography during still video photography. Besides, a logic control unit 21 for controlling the auto iris circuit 209 and the AGC circuit 203,
Reference numeral 2 is a still / movie mode selection switch.

In the recorder section 300, 31 is an A / D conversion circuit for converting the luminance signal Y and the color difference signals BY and RY obtained from the matrix circuit 205 of the camera section 200 into digital signals respectively, and 32 is A / D. A memory circuit that stores the output of the D conversion circuit 31 for one screen, 33 is a rate conversion circuit that reads the image information stored in the memory circuit 32 in accordance with the PCM recording method, and 34 is PCM recording the output of the rate conversion circuit. It is a VTR section.

FIG. 2 is a flow chart showing the overall control procedure in this embodiment. The processing contents of each step (# 1 to # 20) in this figure are as follows.

# 1: It is determined whether it is a still picture (SV) or a movie picture (MV).

# 2: Recording of movie images is permitted.

# 3: When SV is selected in # 1, it is determined whether the strobe is used or whether charging is completed when the strobe is used.

# 4: If charging of the strobe is completed (using the strobe), the current control value of the aperture value / automatic gain control circuit (AGC) is stored.

# 5: AGC / white balance (AW
The value of B) is set to a predetermined value suitable for SV shooting using a flash.

# 6: The shutter speed of the electronic shutter is set to a shutter speed suitable for SV photography using a strobe.

# 7: If the release button is pressed, the strobe light is emitted at a predetermined timing.

# 8: The aperture value, the AGC, and the electronic shutter are returned to the states before they were set for SV photographing.

# 9: Waits for the release button to be pressed when SV shooting without strobe is selected.

# 10: Recording of a still picture is started.

Next, the operation of this embodiment will be described with reference to FIG.

First, the subject image projected by the lens unit 100 is converted into an electric signal by the image pickup device 201 of the camera unit 200. At this time, the mode selection switch 212
When is selected on the movie (MV) mode side,
The logic control unit 211 follows the algorithm shown in FIG.
In the general video shooting mode, the output of the image pickup device 201 is sampled for each pixel by the sample hold circuit 202, and the image signal level becomes proportional to the amount of incident light from the lens unit 100.

The auto iris circuit 209 averages this signal by an appropriate method, drives the IG meter 16 of the lens unit 100 so that the averaged level becomes a predetermined level, and adjusts the aperture value of the aperture 12. adjust.

When the video signal level cannot be adjusted to the predetermined level, the AGC circuit 203 electrically adjusts the amplification degree to automatically adjust the amplification level to the predetermined level.

The video signal thus adjusted is subjected to gamma correction by the gamma correction circuit 204, and converted into a luminance signal and a color difference signal by the matrix circuit 205. The mixture ratio of each color of R, G, B in the matrix circuit 205 is automatically corrected by the AWB circuit 210 so as to obtain an appropriate color balance. This signal is converted into a standardized signal such as NTSC by the encoder circuit 206 and, at the same time, sent to the recorder unit 300 and recorded on a magnetic tape in analog form.

On the other hand, when the mode selection switch 212 is selected to the still (SV) mode side, the logic controller 211 enters the still shooting mode according to the algorithm shown in FIG. Here, the flash unit 400 is externally attached to the camera, and the logic control unit 211 detects whether or not a charge completion signal for the flash unit 400 has been sent. If the strobe unit 400 is not attached, or if the strobe unit 400 is attached but the charging is not completed, the normal still photography mode is set.

In the normal still shooting mode, the luminance signal output and the color difference signal output from the matrix circuit 205 are still recorded in the recorder unit 300. That is, when the shutter release button is pressed, first, each signal output of the brightness and color difference of the image for one frame when the shutter release button is pressed by the A / D converter 31 is converted into a digital signal, and each frame is converted into a digital signal. Memory 32
Remember. The image signal stored in the frame memory 32 is read by the rate converter 33 while performing rate conversion for distributing to a plurality of tracks in the PCM area of the magnetic tape, and subjected to a predetermined PCM encoding process to perform VTR section 34. And PCM recorded on the magnetic tape.

On the other hand, when the strobe unit 400 is attached to the video camera and the charging completion signal is output from the strobe unit 400, the logic control unit 211 judges this and the strobe light emission still photography mode. Becomes

In this strobe light emission photographing mode, the iris encoder 1 is first operated according to the algorithm shown in FIG.
4, aperture value information immediately before flash photography, AGC gain information from the AGC circuit 203 and the AWB circuit 210,
The white balance setting value information is read and stored.

In general, the aperture value is determined by the guide number (hereinafter abbreviated as GNo.) Of the flash unit 400 and the subject distance, and is often different from the aperture value before the flash shooting. In addition, in stroboscopic photography, in general, a subject with low illuminance is often photographed, and in a normal photography mode, the aperture may be open and the AGC gain may be large. Further, the white balance is often set under a color temperature such as room light different from the color temperature of the flash unit 400.

After storing the above three pieces of information, the logic control unit 211 forcibly fixes the AGC circuit 203 to a normal gain or a gain suitable for flash photography, and further
The WB circuit 210 is forcibly set to match the color temperature of the flash unit 400.

The light emission time of the strobe part 400 is usually several hundredths of seconds to several tens of thousands of seconds, and the accumulation time of the image pickup device 201 in general photographing is 1 / 60th of a second in the case of the NTSC system. It is a degree. Therefore, when the illuminance of the subject is large to some extent, in order to avoid the influence of camera shake or the like, it is desirable that the accumulation time is adjusted to the light emission time of the flash unit 400. Therefore, in the logic control unit 211, the image sensor 20
The driver 208 of No. 1 is driven as a so-called electronic shutter, and control is performed so that the accumulation time matches the flash emission time.

After the above settings are made, the flash light is emitted. FIG. 3 shows an algorithm of the logic control unit 211 in this strobe light emission. 4 shows the internal structure of the flash unit 400.

The flow chart shown in FIG. 3 shows in detail the operation at the time of release (flash emission) in step # 7 of FIG. The contents of the illustrated steps (# 11 to # 23) are as follows.

# 11: The guide number (GNo.) For strobe pre-light emission and main light emission is read by the control unit using an electrical communication means or the like. Similarly, subject distance information Dv and focal length information f are input to the control unit by the focus encoder and zoom encoder of the lens.

# 12: The focal length information of the video camera is converted into the focal length of the silver halide camera of the strobe.

# 13: The emission angle of view of the strobe is changed based on the converted focal length information.

# 14: The control unit 211 obtains the aperture value (FNo.) At the time of pre-light emission by the following calculation formula.

[0048]

[Formula 1] FNo. (P) = GNo. ÷ Dv # 15: Waits for the shooting preparation operation to end.

# 16: Confirm the timing of the V sync signal.

# 17: The control unit 211 causes the strobe to issue a command for pre-flashing.

# 18: The video signal level at the time of pre-flashing is detected.

# 19: The proper aperture is obtained by the following calculation from the image detection signal level, the aperture value at the time of pre-light emission, and the predetermined appropriate signal level in the control section.

[0053]

[Equation 2]

# 20: The aperture value is reset to the value obtained by the above calculation.

# 21: Wait for actual shooting release.

# 22: Confirm the timing of the V (vertical) synchronizing signal.

# 23: Main light emission is performed at a predetermined timing.

In the strobe circuit shown in FIG. 4, the power supply 401 is a battery power supply for supplying power to all circuits in the strobe section. The main switch 402 is
This is an operation switch (not shown) on the flash and is operated by the photographer. By turning on the switch 402, power is supplied to each circuit.

The DC / DC converter 403 is a circuit for producing a high voltage for causing the strobe xenon tube to emit light. The high voltage output of the DC / DC converter 403 is charged in the pre-capacitor 404. At the same time, the main capacitor 411 is also charged via the diode 406.

When the charging voltage of the main capacitor 411 reaches a predetermined level, the charge completion detecting circuit 408 outputs a detection signal. This detection output is input to the microcomputer 412 that controls all strobe control. Then, this charging completion signal is transmitted to the television camera side via the direct contact 418 with the camera side.

Guide number GNo. Indicating the main flash emission amount. Is also transmitted to the camera side via the camera direct connection contact 418. The guide number changes depending on the zoom position of the strobe (light emission screen). These communications are performed by digital serial communications.

The information sent from the camera-side logic control unit 211 via the camera direct contact 418 includes lens focal length information. If you use a general-purpose strobe for a 35mm film camera, its focal length is 50m.
If m, a standard angle of view, a number larger than 50 mm is a telephoto angle of view, and a number smaller than 50 mm is a wide angle of view.

The standard angle of view of the video camera is determined by the area of the image pickup device 201 used in the camera. For example, when a 1/2 inch size CCD is used as an image sensor, the standard angle of view is about 8 mm in focal length. On the camera side, the logical control unit 211 obtains the focal length information of the lens from the output of the zoom encoder 14, converts the focal length information into the focal length information of the film camera of 35 mm, and transmits it to the strobe side.

Upon receiving this information, the microcomputer 412 compares the output of the zoom position detection circuit 413 by the zoom encoder of the strobe with the motor driver 415 so as to control the zoom motor 414 of the strobe in the forward or reverse direction. Output.

By the operation at the standard stage of still image shooting on the camera side (for example, the first stroke of the still image release button, etc.), the logical control unit 211 on the camera side follows the algorithm shown in FIG. The signal is sent to the microcomputer 412 via the camera direct connection contact 418. When the microcomputer 412 receives this signal, the microcomputer 412 outputs a pre-trigger signal to the pre-trigger circuit 407.

The pre-trigger circuit 407 includes a pre-discharge tube 40.
A trigger signal is generated at 5, and the pre-discharge tube performs pre-light emission by the charge accumulated in the pre-capacitor 104.

On the camera side, the pre-flash guide number information GNo. (P), main light emission guide number information GNo. (M), a predetermined calculation GNo. ÷ Dv (m) = FNo. And then
The F number (FNo.) Of the aperture is calculated.

This object distance information is obtained by detecting the output of the focus encoder 13 when the AF operation of the camera is performed and the focus state of the lens is in focus by the logic control unit 211.

However, since the object distance information has an error particularly at a longer distance, it becomes difficult to obtain accurate strobe exposure. Especially in the case of a video camera, unlike a silver halide film, since the dynamic range with respect to brightness is narrow, it is necessary to further consider it for proper exposure.

In the present configuration shown in FIG. 4, according to the algorithm shown in FIG. 3, the automatic control of the auto iris circuit 209 is canceled by the logic control unit 211, and the IG meter 16 is forcibly set to the above aperture value. It is driven to perform pre-light emission with a low light amount at the aperture value calculated above. This pre-flash makes a pseudo exposure before the main shooting,
Appropriate exposure is obtained in main light emission by automatically re-appearing the aperture value.

For example, a video signal of a subject image illuminated by pre-emission is obtained by the image pickup device 201 and the sample hold circuit 202, and this signal is supplied to the logic controller 211.
To the appropriate signal level of the image signal level of the subject irradiated by the pre-emission with the logic control unit 211, and an appropriate aperture value FNo.
(M) is obtained by the following calculation.

[0072]

[Equation 3]

The FNo. (M) Based on the information, the logic control unit 211 causes the auto iris circuit 2 to
The IG meter 16 is driven via 09 to set the aperture value.

Then, the main light emission signal is sent from the camera side to the microcomputer 412 via the camera direct connection contact 418 by the operation of the main photographing (for example, the second stroke of the still image release button). When the microcomputer 412 receives this signal, the microcomputer 412 sends a main trigger signal to the main trigger circuit 409.
Output to. The main trigger circuit 409 causes the main discharge tube 410 to generate a trigger signal, and the main discharge tube emits main light by the charge accumulated in the main capacitor 411.

With respect to the pre-emission and the main emission, the light is emitted immediately after the shutter curtain is opened in a general film camera, but in the video camera, it is necessary to emit the light within the accumulation time of the image pickup device 201 during the scanning of the screen. Therefore, in the logic control unit 211, the vertical synchronizing signal of the camera is detected by the SSG circuit 207, and the light is emitted within the accumulation time of the CCD according to the algorithm shown in FIG.
Send the pre-flash and main flash trigger signals.

After the flash emission is completed through the above process, based on the algorithm shown in FIG. 2, the aperture value, A
The auto iris circuit 209, the AGC circuit 203, and the AWB circuit 210 are respectively set so that the GC gain and the white balance set values return to the values stored immediately before the flash photography.
Control and reset.

On the other hand, the video signal obtained by the light emission of the strobe section 400 is sent to the recorder section 300, and PCM recording is carried out in the same manner as in the ordinary still picture photographing.

[0078]

As described above, according to the present invention, when a still image is recorded by using an auxiliary light emitting element such as a strobe, the white balance set value immediately before the recording of the still image is stored in advance. Every time, when the still image recording is finished, the previously stored white balance setting value can be immediately returned, so that it is possible to obtain a good white balance even when recording a moving image immediately after using a flash etc. .

[Brief description of drawings]

FIG. 1 is a block diagram showing an entire embodiment of the present invention.

FIG. 2 is a flowchart showing the overall operation of FIG.

FIG. 3 is a flowchart showing in detail the processing contents of step # 7 shown in FIG.

FIG. 4 is a detailed circuit configuration diagram of a flash unit.

FIG. 5 is an explanatory diagram of a conventional technique.

FIG. 6 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 100 lens unit 200 camera unit 201 image sensor 210 AWB circuit 211 control unit 212 mode selection switch 300 recorder unit 400 strobe unit

Claims (1)

[Claims] 1. In an image recording apparatus having an automatic white balance function and capable of switching between moving image recording and still image recording, when the auxiliary light emitting device is operated during still image recording, A correction unit that corrects the white balance according to the emission characteristics, a storage unit that stores the white balance setting value immediately before the still image recording, and a white balance that is stored in the storage unit after the still image recording is finished. An image recording apparatus comprising: a control unit that restores the white balance set value that has been set.